Kosuke Katsurayama

Neutron Radiography Application to Ancient Arts

Neutron radiography testing (NRT) has been applied to several ancient relics at Kyoto University Research Reactor and the cyclotron-based facility of Sumitomo Heavy Industries, Ltd. Some of the results are presented with comments on the usage and applicability of NRT. The objects studied are an excavated bronze mirror with four bells (late 5c.A.D. to early 6c.A.D.), an unearthed corroded bronze mirror with cloth (4c.A.D.), unearthed Buddhist sutras in a bronze case (10c.A.D.), a Tibetan unglazed Buddhist statue cushioned with cloth in a copper box with a window and an excavated iron sword conserved and restored (4–5c.A.D.). From comparisons with X-ray radiography testing, it has been found that NRT can well identify the stones located inside the bells and suggest the casting procedure. Moreover, NRT has been found to be remarkably effective for elucidating unobserved organic objects in bronze fine arts.

Present Status of Neutron Radiography in Japan

In Japan, a series of domestic symposium on neutron radiography have been periodically held at Research Reactor Institute, Kyoto University (KURRI) every two years since November 1970. In April 1984, the Research Committee on Neutron Radiography has been organized by the Irradiation Development Association and the Science and Technology Agency of the Japanese Government, which is held every three months.

Cyclotron-based Real-Time Neutron Radiography System

A real-time neutron radiography system was installed by using a sub-compact cyclotron as a neutron generator. We utilized the neutron radiography facilities of Sumitomg Heavy Industries, Ltd. in which nominal neutron flux is 1.1 × 106 n/cm2 /sec at L/D = 30 with field size of 14″ × 17″.

Characteristics of Neutron Radiography Systems Using Accelerators and a Research Reactor

The equipments for neutron radiography using a 1-MeV Van de Graaff type accelerator and a 18-MeV electron linac of the Radiation Center of Osaka Prefecture (ORC) and Kyoto University Research Reactor (KUR) were set up. The characteristics of neutron beam and the radiographic image qualities with various films available were measured by a Beam Purity Indicator and a Sensitivity Indicator approved by ASTM and a System Image Quality Indicator devised by Barton.